The episode has been a centerpiece of special counsel Robert S. Mueller III's investigation of whether there was any collusion between the Trump campaign and Russia. And now we know much more about what the people who were there said under oath about it.

Here are some key findings.

1. Trump Jr. was clearly anxious for dirt on Hillary Clinton

One line from Trump Jr.'s email exchange with a publicist for a Russian musician stood out: “I love it.” Publicist Rob Goldstone had said his source could provide “official documents and information that would incriminate Hillary and her dealings with Russia" and said the information came from Russia's "crown prosecutor." (That position doesn't technically exist in Russia but does exist in Goldstone's native Britain and is roughly equivalent to attorney general.)

Trump Jr.'s response: “Seems we have some time and if it’s what you say I love it especially later in the summer.”

In his testimony to Congress, Trump Jr. confirmed that he was talking about the opposition research when he said “I love it.”

Question: "What was the 'it' that you loved in that e-mail?"Trump Jr: "Potential information about an opponent." pic.twitter.com/495f2Xnm49

This is key because Trump Jr. wasn't completely clear about what he was talking about in the email. It suggests that he was eager to have the meeting specifically because of the opposition research that was supposedly being supplied by official sources in the Russian government. His initial explanation of the meeting suggested that it was primarily about adoptions, although that explanation quickly fell apart.

Other witnesses also suggested Trump Jr. was eager to get dirt. Russian lobbyist Rinat Akhmetshin told senators Trump Jr. started the meeting by saying something like, "So you have some information for us?" Ike Kaveladze, an American-based employee of a Russian real estate company and who was at the meeting, said Trump Jr. asked "if they got anything on Hillary."

2. Trump Jr. says President Trump may have personally influenced misleading explanations about the meeting

Trump Jr. said he didn't know about his father's direct involvement and actively discouraged it, but he said he thinks Trump may have influenced the messaging about the meeting through then-White House communications aide Hope Hicks:

Q. To the best of your knowledge, did the president provide any edits to the statement or other input?

A. He may have commented through Hope Hicks.

Q. And do you know if his comments provided through Hope Hicks were incorporated into the final statement?

A. I believe some may have been, but this was an effort through lots of people, mostly counsel.

3. Trump Jr. says he doesn't recall whether a key call with a blocked phone number was his father

It came June 6 shortly after a call with Russian pop star Emin Agalarov about the meeting, but we don't know whom it was with was from because the number was blocked. A big question has been whether it was his father, and whether Trump Jr. might have informed his father about the meeting on that call. (The elder Trump has also denied knowing about the meeting.)

Former Trump campaign manager Corey Lewandowski has testified that the president's primary residence utilizes a blocked number, but Trump Jr. said in testimony that he doesn't recall whether the call was with his father:

Q. Does your father used a blocked number on his cellphone or on any phones that you call him on?

June 6, 4:27 p.m.: Trump Jr. is in contact with a blocked number. It lasts for four minutes. It’s not clear if the call was outgoing or incoming; the testimony suggests that it was incoming but a report from Senate Democrats suggests it was outgoing. (The phone records are redacted in the documents released on Wednesday.)

Goldstone's initial email to Trump Jr. said the information came from the Russian government. This suggests he wasn't guessing or speaking loosely.

5. Meeting attendees say no valuable information was provided

It's clear that Trump Jr. intended to get opposition research from Veselnitskaya in the meeting, but part of his defense has long been that he was unsuccessful in doing so — that the meeting was a bust. So even if you believe that the meeting represented attempted collusion with a Kremlin-aligned lawyer, the whole thing never actually came to fruition.

And people who attended the meeting generally agreed that it didn't include the transmission of damaging information.

“I don't know what would be deemed ‘damaging,’ but I didn't hear anything that I would deem to be damaging,” Goldstone said. “And I didn’t see anybody react in a way that I believed people would react if they heard damaging information.”

Goldstone said at another point: "I said to [Trump Jr.], 'Don, I really want to apologize. This was hugely embarrassing. I have no idea what this meeting was actually about."

Trump Jr. also reiterated, under oath, that the meeting was a waste of time: “All else being equal, I wouldn’t have wanted to waste 20 minutes hearing about something that I wasn’t supposed to be meeting about.”

6. Goldstone vented about the meeting being “an awful idea” after investigators grilled him

In an email to Agalarov in June 2017, Goldstone expressed concern that the investigation was becoming very serious and said he regretted the whole thing. “I did say at the time this was an awful idea and a terrible meeting,” he wrote.

Rob Goldstone, who set up the Trump Tower meeting, grew frustrated a year later and vents to his longtime client Emin Agalarov. "I did say at the time this was an awful idea and a terrible meeting.” pic.twitter.com/AGaiEx0UjO

(Side note: The email describes the meeting being set up in October. Goldstone told the committee that he simply misstated the month. He blamed it on the "fact that I'm now 57 and demented. I mean the June meeting.")